Kelp Laminaria hyperborea plants support a diverse epiflora and epifauna with
their holdfasts forming a sheltered habitat for a diverse assemblage of animals. However L.
saccharina forests are subject to intense grazing by urchins and chitons and tend to
have poorly developed seaweed communities. Those species which are present are typically
silt-tolerant and include a high proportion of delicate filamentous types.

Recruitment processes

Kelp biotopes are important nursery areas for a diverse range of species. It is likely
that juvenile forms of all the animals that are present as adults in the kelp bed make use
of the habitat as a nursery area. Rinde et al. (1992) states that the kelp beds in
Norway are nursery areas for gadoid species. Other species may make use of the kelp beds
during only parts of their life cycles. Specific information on the extent to which UK
kelp biotopes are used as nursery areas for animal species is not known.

Productivity

Kelp plants are the major primary producers in the marine coastal habitat. Within the
euphotic zone (from high water to the depth of light penetration) kelps produce nearly 75%
of the net carbon fixed.

Keystone (structuring) species

Laminaria saccharina, L. hyperborea, Echinus esculentus

Importance of habitat for other species

Although kelp species often dominate their environment, they also supply extra
substrate available for other organisms. Holdfasts also provide refuge to a wide variety
of animals. Jones (1971) listed upto 53 macrofaunal invertebrate species obtained from an
individual holdfast. A few meiofaunal species may actively burrow into kelp. Benwell
(1981) has shown how the nematode Monhystera disjuncta may help weaken the distal
areas of the kelp where it feeds on decomposition-associated microbiota.

Temporal changes

Long-term fluctuations or permanent shifts in the biodiversity of kelp beds may occur
in the UK; however long-term monitoring has not been undertaken. Long-term studies on kelp
beds on the Atlantic coast of Canada have continued since the original study in the late
1960s (Mann 1972). Temporal changes within kelp beds seem to be on a decadal scale,
making monitoring projects of very long term a necessity.

Time for community to reach maturity

Leinaas & Christie (1996) examined re-colonisation of a barren kelp forest after
severe reductions in urchin numbers. The succession of algal growth followed a predictable
pattern. The substratum was colonised initially by filamentous algae and then by Laminaria
saccharina.